Advances in magnetic resonance imaging (MRI) are driving the development of MRI machines with static magnetic fields (MFs) of 4 - 9 tesla (T); however, little is known about the sensory or physiological effects high strength MFs produce in mammals or humans. Recently, our lab demonstrated that exposure to high strength MFs produces behavioral and neural effects in male rats and mice. Behaviorally, MF exposure induced circling and conditioned taste aversion (CTA). There are sex and estrous cycle differences in these behaviors suggesting that the behavioral response to MF is dependent upon ovarian steroids. At the neural level, MF exposure induced c-Fos in brainstem visceral and vestibular nuclei. These effects are similar to the effects of vestibular disturbance, such as rotation. We hypothesize that MF exposure activates the rat's vestibular apparatus and that there is a sex difference in the response to MF exposure such that females show enhanced circling and more persistent CTA. Therefore, I plan to demonstrate, using c-Fos, a neural response that parallels behavior, and using LCM and RT-PCR, the presence of steroid receptors in the vestibular system. These experiments will contribute to the understanding of the neural pathways underlying these effects. In addition, these experiments may help predict the effects of high-strength MRI on humans. [unreadable] [unreadable]